Acute consumption of walnuts and walnut components differentially affect postprandial lipemia, endothelial function, oxidative stress, and cholesterol efflux in humans with mild hypercholesterolemia

J Nutr. 2013 Jun;143(6):788-94. doi: 10.3945/jn.112.170993. Epub 2013 Apr 24.

Abstract

Walnut consumption improves cardiovascular disease risk; however, to our knowledge, the contribution of individual walnut components has not been assessed. This study evaluated the acute consumption of whole walnuts (85 g), separated nut skins (5.6 g), de-fatted nutmeat (34 g), and nut oil (51 g) on postprandial lipemia, endothelial function, and oxidative stress. Cholesterol efflux (ex vivo) was assessed in the whole walnut treatment only. A randomized, 4-period, crossover trial was conducted in healthy overweight and obese adults (n = 15) with moderate hypercholesterolemia. There was a treatment × time point interaction for triglycerides (P < 0.01) and increased postprandial concentrations were observed for the oil and whole walnut treatments (P < 0.01). Walnut skins decreased the reactive hyperemia index (RHI) compared with baseline (P = 0.02) such that a difference persisted between the skin and oil treatments (P = 0.01). The Framingham RHI was maintained with the oil treatment compared with the skins and whole nut (P < 0.05). There was a treatment effect for the ferric reducing antioxidant potential (FRAP) (P < 0.01), and mean FRAP was greater with the oil and skin treatments compared with the nutmeat (P < 0.01). Cholesterol efflux increased by 3.3% following whole walnut consumption in J774 cells cultured with postprandial serum compared with fasting baseline (P = 0.02). Walnut oil favorably affected endothelial function and whole walnuts increased cholesterol efflux. These 2 novel mechanisms may explain in part the cardiovascular benefits of walnuts.

Trial registration: ClinicalTrials.gov NCT00938340.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cell Line
  • Cholesterol / blood
  • Cholesterol / metabolism
  • Diet*
  • Dietary Carbohydrates
  • Dietary Fats
  • Dietary Proteins
  • Endothelium, Vascular / physiopathology
  • Energy Intake
  • Female
  • Heart Rate
  • Humans
  • Hypercholesterolemia / blood
  • Hypercholesterolemia / physiopathology*
  • Juglans*
  • Lipids / blood
  • Macrophages / metabolism
  • Male
  • Middle Aged
  • Nuts*
  • Obesity / physiopathology
  • Overweight / physiopathology
  • Oxidative Stress / physiology
  • Postprandial Period*

Substances

  • Dietary Carbohydrates
  • Dietary Fats
  • Dietary Proteins
  • Lipids
  • Cholesterol

Associated data

  • ClinicalTrials.gov/NCT00938340